A rare type of iridescent, shining cloud that was forecast to become much more common and visible this summer has, so far, failed to live up to the hype — and the increasingly volatile sun may be to blame.
Noctilucent clouds (NLCs), or night-shining clouds, are a type of mesospheric cloud. As the name suggests, mesospheric clouds form in the mesosphere, the third layer of Earth's atmosphere, which stretches between 31 and 50 miles (50 and 80 kilometers) above Earth's surface. NLCs are created when atmospheric water vapor freezes into ice crystals that stick to particles of atmospheric dust left behind by meteor showers and volcanic eruptions.
